Idea Summary
When you want to run a modal dialog from the page designer, it doesn't allow you to do so. I understand that you need a parent page for modal dialogs, but when you are just debugging or designing the page components, is quite frustrating having to open the app and navigate to that modal dialog.
Use Case
Avoid unnecessary clicks for running modal dialogs, better development experience.
Preferred Solution (Optional)
When you run a modal dialog page, it could load over a blank temporary page with the standard theme page template instead of not allowing it.